The present invention relates to an improved quick adjustment nut, and in particular to a quick release stop and guide for use on drilling, depth milling and other machinery.
In general, stops and guides for use on drilling, depth milling and other similar machinery are known. For example, a portion of a commercially available "Bridgeport" vertical milling machine is shown in FIG. 1. A quill 10 is associated reciprocated in accordance with manual control by handle 12 within prescribed limits defined by a stop nut 18 and lock nut 20. Stop nut 18 and lock nut 20 are threadedly mounted on a length threaded shaft 16 attached to the milling machine. A solid quill stop 14 is coupled to (and moves with) quill 10. The respective nuts cooperate to regulate the drilling and milling depth setting of the quill in a manner well known to machine shop operators.
However, quill 10 has a travel range of on the order of five inches and a depth stop may be required at any point along this range. Accordingly, in the past much time has been wasted in manually threading the movable nuts up and down the threaded rod. The latter operation is especially time consuming and irritating when the threads are dirty and while the operator is engaged in producing short-run lots of work, each requiring a different stopping position of the movable nuts on the shaft. Often, because of this inconvenience, the operator will not use the movable nuts, preferring instead to sight depth by eye with the aid of the five-inch scale 21 attached to the machine. In addition, the stop nuts typically do not include any graduation to facilitate precision adjustment, and even when the stop nuts are used in short-run lots, operators tend to adjust the nuts merely by sight, rather than accurately measuring the depth of the quill. The result is thus less accurate work than would be the case if the stop and lock nuts were used properly.
Quick release nuts which provide for selective sliding or threading motion with respect to a threaded shaft are known. An example of such a nut is described in U.S. Pat. No. 422,361 issued to G. H. Alton on Mar. 4, 1890. The Alton nut is formed of a body including an axial bore therethrough, and a transverse bore communicating with the axial bore. A thumb piece, including a transverse bore, is received in the body transverse bore such that the thumb piece transverse bore is in general registry with the body axial bore. The thumb piece bore (and body axial bore) are of a constant diameter sufficiently larger than the diameter of the threaded shaft with which the nut is to cooperate, to permit reception of the threaded shaft with a considerable space allowed for play. A portion of the interior of the thumb piece bore is threaded in a manner suitable for engagement with the threads of the shaft and the thumb piece is spring biased to bring the threaded portion into engagement with the shaft threads. Depressing the thumb piece against the spring bias, disengages the threaded portion of the thumb piece bore from the threaded shaft, and the play in the bore diameter permits sliding of the nut with respect to the shaft. However, the use of a thumb piece bore of a constant diameter significantlly larger than the diameter of the shaft, effects only a relatively small threaded engagement (significantly less than 180 degrees) between the shaft perimeter and nut. Accordingly, the nut is relatively susceptible to spurious disengagement or movement due to, for example, vibration of the threaded shaft or unintentional physical contact on the nut by an operator. Moreover, the thumb piece of such nuts commonly protrude from the nut body to such an extent that the relative position of the threaded shaft and body of a conventional milling machine would preclude motion of the nut. Moreover, no gradations are provided to facilitate fine adjustment. Thus, such prior art quick release nuts do not provide sufficient precision or stability for use with, for example, a conventional milling machine.
Attempts have been made to provide nuts which can be easily, and accurately set to selected locations on threaded rods associated with milling machines. Examples are disclosed in U.S. Pat. Nos. 3,431,623 issued Mar. 11, 1969 to G. G. F. Smeets and 4,084,897 issued Sept. 20, 1977 to E. E. Price, Jr. However, such prior art releasable nuts are subject to a number of serious disadvantages. The devices are relatively complex and expensive to manufacture. Moreover, internal portions of the nuts tend to be exposed and are thereby subject to jamming due to the accumulation of metal chips lodging in the exposed portions. Moreover, the nuts lack precision adjusting graduations.